Download - PLS 2016: Exploring daylight metrics
Exploring Daylight MetricsLongyu GuanJemima Unwin
Part 1: A look at current daylight metricsPart 2: The potential of volumetric lighting metricsPart 3: Challenges and ongoing research of new metrics
Exploring Daylight Metrics
Daylight Factor approach: x 100%
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A look at current daylight metrics
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Direct Component
External Reflected ComponentInternal Reflected Component
Overcast Sky
A look at current daylight metrics
Daylight Factor approach: x 100%
Overcast Sky
A look at current daylight metrics
Daylight Factor approach: x 100%
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Direct Component
External Reflected ComponentInternal Reflected Component
Overcast Sky
A look at current daylight metrics
Daylight Factor approach: x 100%
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Direct Component
External Reflected ComponentInternal Reflected Component
Overcast Sky
In real life practiceā¦Climate-based Daylight Modellingā¢ Daylight autonomy ā¢ Useful daylight illuminanceā¢ Annual sunlight exposure
Climate Data
Similar process & the same āworking planeā
A look at current daylight metrics
Working environment in the 1970s
Working environment nowadays
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Working PlaneāVisual Performanceā
Perceived Daylight Adequacy
Whole SpaceāVolumetricā
Cylindrical illuminance:
2DISinEcyl
EN 12464-1 (2002)āāWorking planeā removedāRecommended illuminance on major room surfacesāMean cylindrical illuminance (2011)
The potential of volumetric lighting metrics
Cylindrical illuminance:
2DISinEcyl
1.2 m
EN 12464-1 (2002)āāWorking planeā removedāRecommended illuminance on major room surfacesāMean cylindrical illuminance (2011)
The potential of volumetric lighting metrics
Cylindrical illuminance:
2DISinEcyl
1.6 m
EN 12464-1 (2002)āāWorking planeā removedāRecommended illuminance on major room surfacesāMean cylindrical illuminance (2011)
The potential of volumetric lighting metrics
Cubic Illuminance
The potential of volumetric lighting metrics
Can we make volumetric lighting metrics simpler?
Cubic Illuminance
The potential of volumetric lighting metrics
Exitance
Incident flux
Exitance
The potential of volumetric lighting metrics
Incident flux
Exitance
Average exitance of all Room surfaces
Exitance
The potential of volumetric lighting metrics
MRSE =
MRSE
Mean Room Surface Exitance (MRSE)
Exitance
The potential of volumetric lighting metrics
Why MRSE has good potential as a daylight metric
1. A new term, but established concept
Overcast Sky
MRSEIRC
The potential of volumetric lighting metrics
2. Simplicity
ā¢ One single number
Why MRSE has good potential as a daylight metric
1. A new term, but established concept
The potential of volumetric lighting metrics
ā¢ One single numberā¢ Can be easily calculated (to a first approximation)
Total flux entering the room()
Room surface area & reflectance ( & R)
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2. Simplicity
Why MRSE has good potential as a daylight metric
1. A new term, but established concept
The potential of volumetric lighting metrics
3. Correlates well with electrical lighting guidance
EN12464-1(Lighting of indoor work places)
Recommendsilluminance on
major room surfaces
Reflectance of room surfaces
Effectively forced a minimum MRSE value
2. Simplicity
Why MRSE has good potential as a daylight metric
1. A new term, but established concept
The potential of volumetric lighting metrics
So far we only considered daylighting in a āboxāā¦
However in real lifeā¦
So far we only considered daylighting in a āboxāā¦
However in real lifeā¦However in real lifeā¦
Problems with MRSE approach:
Challenges and ongoing research of new metrics
MRSE starts to break down when the building is open-planned and geometrically more complicated
Essence of MRSE:
MRSE
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Cubic Illuminance
Challenges and ongoing research of new metrics
Cubic Illuminance
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Challenges and ongoing research of new metrics
Essence of MRSE:
Direct Illuminance
Indirect Illuminance
Cubic IlluminanceIndirect Illuminance
Challenges and ongoing research of new metrics
Essence of MRSE:
Cubic Illuminance Indirect Illuminance
Challenges and ongoing research of new metrics
Essence of MRSE:
Indirect Illuminance
Challenges and ongoing research of new metrics
Essence of MRSE:
Indirect Illuminance
Challenges and ongoing research of new metrics
Essence of MRSE:
Indirect Illuminance
Challenges and ongoing research of new metrics
Essence of MRSE:
Average Indirect Illuminance (of the space)
Indirect Illuminance
Challenges and ongoing research of new metrics
Essence of MRSE:
Average Indirect Illuminance (of the space)
Challenges and ongoing research of new metrics
Essence of MRSE:
A pilot study on the new metrics: ā¢ The Heelis building (HQ of national trust)
Challenges and ongoing research of new metrics
Scale 1 to 7:
ā¢How is the lighting overall?ā¢How is the natural lighting overall?ā¢ Is there any glare from natural lighting?
Plus respondentsā comments Respondentsā working desk can be traced back.
A pilot study on the new metrics: ā¢ The Heelis building ā¢ BUS datasets
Challenges and ongoing research of new metrics
- Daylight Factors (DF) & Average Indirect Illuminance (AIE)- Overcast Sky with external illuminance of 10,000 lx
A pilot study on the new metrics: ā¢ The Heelis building ā¢ BUS datasetsā¢ Computer simulation (Radiance)
Challenges and ongoing research of new metrics
DF: 7.2%AIE: 164 (1.6%)
DF: 2.1%AIE: 75 (0.7%)
DF: 5.2%AIE: 213 (2.1%)
Heelis Building-Data source: Roderic Bunn BSRIA/UCL
1 2 3 4 5 6 7-10%
0%
10%
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40%
50%
60%
1 2 3 4 5 6 70%
10%
20%
30%
40%
50%
60%
1 2 3 4 5 6 7-10%0%
10%20%30%40%50%60%
ratings
ppl %
Challenges and ongoing research of new metrics
ā¢ AIE encourages shading + large window
ā¢ AIE encourages high room surface reflectance
ā¢ AIE represents daylight in the whole space
ā¢ Reasons to believe AIE better reflects peopleās perception of daylight adequacy
Challenges and ongoing research of new metrics
Difficulties of testing new metrics:
- Data selection
Further research:- More real life case studies- Compare the performance of different daylight metrics- Explore the CBDM potential of new metrics
Metrics can only be reliably tested in many real buildings
- Validity- Comparing different metrics What should I
have for lunch?Pfffffā¦ just tick the middle score
Challenges and ongoing research of new metrics
